• 1998 Seed Treatment Evaluations

      Norton, Eric C.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Cottonseed was treated with several fungicide treatments in an effort to protect the seed and seedling from disease. Seed germination and vigor was evaluated in three Arizona locations; Maricopa, Marana, and Safford. Stand counts were taken after emergence at all three locations and percent emergence (PEM) was calculated. Significant differences in percent emergence due to seed treatments were observed in the both sample dates at Marana. Maricopa and Safford showed no statistically significant differences due treatment.
    • The 1999 Arizona Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, Jeffrey C.; Ellsworth, Peter C.; Olsen, Mary W.; Husman, Stephen H.; Walser, R.; Clark, L.; Dunn, D.; Schneider, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Arizona Cooperative Extension generates and distributes weather-based Planting Date and Cotton Development Advisories for 19 cotton production areas (Aguila, Buckeye, Cochise Co., Coolidge, Eloy, , Laveen, Litchfield Pk., Marana, Maricopa, Mohave Valley, Paloma, Parker, Pinal Co., Queen Creek, Roll, Safford and Yuma Valley). Planting Date Advisories are distributed from legal first planting date until the end of April and provide updates on heat-unit-based planting windows, recent and forecasted weather conditions, heat unit accumulations, variety selection, soil temperatures, recommended plant population, and early insect management and control. Cotton Development Advisories are distributed from early May through early September and provide updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1999, and growers may obtain advisories by mail/fax from local extension offices or by computer from the AZMET Internet Web Page (http://ag.arizona.edu/azmet). Major program changes planned for 1999 include 1) use of historical AZMET weather data for local normals and 2) elimination of the computer bulletin board as a computer-based means of retrieving the advisories.
    • Short Staple Regional Cotton Variety Trial, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Forty eight short staple varieties were grown in a replicated field trial on the Safford Agricultural Center. Excellent yields were recorded, especially considering the late start caused by unseasonably cold weather in April. FM 989, the Australian variety formerly known as IF 1003, produced the highest lint yield of 1601 pounds per acre. Three other varieties, FM 975, AP 4103 and IF 1002, produced over 1500 pound of lint per acre. Agronomic values for the plants at harvest and HVI data for lint quality are tabulated in this paper.
    • Mortality Factors Affecting Whitefly Populations in Arizona Cotton Management Systems: Life Table Analysis

      Naranjo, Steven E.; Ellsworth, Peter C.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ and 2University of Arizona, Maricopa, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Direct-observation studies were conducted in replicated experimental plots to identify causes and estimate rates of mortality of whiteflies in cotton over the course of six generations from late June through late October. In plots receiving no whitefly or Lygus insecticides, predation and dislodgment were major sources of egg and nymphal mortality, and overall survival from egg to adult ranged from 0-18.2%. Similar patterns were observed in plots treated with the insect growth regulator (IGR) Knack. Applications of the IGR Applaud or a mixture of endosulfan and Ovasyn caused high levels of small nymph mortality and reduced rates of predation on nymphs during the generation immediately following single applications of these materials in early August. Whitefly populations declined to very low levels by mid-August in all plots, and few differences were observed in patterns of whitefly mortality among treated and control plots 4-6 weeks after application. The population crash was associated with an unknown nymphal mortality factor which reduced immature survivorship during this first posttreatment generation to zero. The application of insecticides for control of Lygus in subplots modified patterns of mortality in all whitefly treatments by generally reducing mortality from predation during generations observed from mid-July through August. Parasitism was a very minor source of mortality throughout and was unaffected by whitefly or Lygus insecticides.
    • Preliminary Evaluation of the "Next Generation" of Bt Cotton

      Sieglaff, D. H.; Ellsworth, Peter C.; Silvertooth, Jeffrey C.; Hamilton, E.; Silvertooth, Jeff; The University of Arizona, Department of Entomology & Maricopa Agricultural Center; Department of Plant Sciences; Monsanto Company, Chesterfield, MO (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      The next generation of Bollgard® cotton was evaluated for agronomic and insecticidal efficacy under central Arizona growing conditions. Two novel lines were compared with their recurrent parents, DP50 and DP50B. There were no seasonlong differences observed among the varieties in most plant development and insect parameters. However, DP50 had significantly lower emergence than the other lines tested (possibly related to seed quality). The lower plant population may have been responsible for greater whitefly abundance observed on two dates mid-season. During early-season ratings of secondary “pests” (15 DAP) (scaled on damage and/or presence), the two test lines received lower ratings for thrips and flea beetle when compared with DP50, DP50B and DP50Bu (untreated for Lepidoptera). However, these difference are likely as a result of the difference in seed treatments that the two test lines received (Gaucho®) and the others did not. This seed treatment does have known activity against thrips and beetle pests. In mid-season, the two test lines received lower ratings for beet armyworm when compared to DP50, DP50B and DP50Bu (although, not significantly different from DP50B or DP50Bu). Efficacy against pink bollworm (PBW) was assessed one time at the end of the season (we were limited to this time, so as to not affect yield), and DP50 was the only variety in which PBW exit holes were observed and PBW larvae collected. However, the low Lepidoptera pressure experienced during the season limited assessments of the two novel lines’ efficacy toward PBW. There was no significant difference in yield (bale/A) among the varieties. Although, one of the test lines had a lower lint turnout than each other variety. The two novel Bollgard lines performed well under our growing conditions, but continued evaluations will be necessary under more conditions and more insect pressures before “varietal” performance and gene efficacy can be assessed adequately.
    • Evaluation of the Effects Added Nitrogen Interaction on Nitrogen Recovery Efficiency Calculations

      Norton, Eric R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Two studies were conducted in 1996 and 1997 at the University of Arizona Maricopa Agricultural Center (MAC) to evaluate the added nitrogen interaction (ANI) or ‘priming effect’ on the determination of nitrogen recovery efficiencies (NRE). The method employed was to compare NRE’s as calculated by two different methods; the difference technique and the isotopic technique. The difference in NREs observed between the two methods indicates the extent of an ANI. Results demonstrated no statistical differences between NRE’s calculated by the two methods. Therefore, no ANI was observed in the field. These results indicate that the less expensive method of calculating NREs (difference technique) is sufficient under irrigated cotton production systems in the desert Southwest.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1998

      Silvertooth, Jeffrey C.; Norton, Eric R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Two field experiments were conducted in Arizona in 1998 at two locations (Maricopa and Marana). The Maricopa experiment has been conducted for nine consecutive seasons, the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for Upland cotton. The experiments each utilized N management tools such as pre-season soil tests for NO3 --N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location. In 1998, fruit retention levels were low and crop vigor was high. As a result, even slight increases in N fertilization and crop vigor translated into lower yield.
    • Arizona Upland Cotton Variety Testing Program, 1998

      Silvertooth, Jeffrey C.; Norton, Randy; Clark, L.; Walser, R.; Husman, Stephen H.; Knowles, Tim; Moser, H.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Ten field experiments were conducted in major cotton growing areas of Arizona in 1998 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Eight commercial cottonseed companies participated in the program. A maximum of two varieties were submitted by each company at each location. Experiments were conducted on a commercial level on grower-cooperator fields in most cases. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 100 ft. to 4,000 ft. elevation. Each of the participating seed companies offer a compliment of varieties that can serve to match various production strategies commonly employed in the state. The 1998 cotton season was a very difficult one for many cotton producing areas in AZ below ~2,000 ft. elevation, characterized by a cool wet spring, late planting, a delayed crop, and a strong monsoon season that reduced fruit retention in many cases. Many varieties commercially available performed well at several locations demonstrating good adaptation to Arizona conditions.
    • Date of Planting by Long Staple and Short Staple Variety Trial, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Four varieties each of Long Staple and Short Staple cotton were tested over four dates of planting in this study. The first date of planting for the Long Staple cotton was delayed to the 3rd of April because of poor weather earlier. The latest planting was May 13th. Cultivars of differing maturities were tested for both long and short staple cotton to determine their optimal planting time. Many agronomic and hvi values were evaluated to determine the effect of different planting dates.
    • Upland Cotton Lint Yield Response to Several Soil Moisture Depletion Levels

      Husman, Stephen H.; Johnson, K.; Wegener, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Upland cotton lint yield response to several soil moisture depletion levels was measured in 1997 and 1998. In 1997, four Upland cotton varieties including DP 5415, DP 33B, DP 5816, and STV 474 were tested. However because of a nonsignificant variety difference in the 1997 test, the 1998 test was planted to a single variety (DP 33B). In 1997 and 1998, depletion of plant available soil water (PAW) irrigation treatments consisted of 35%, 50%, 65%, and 80%. In 1997, all PAW depletion treatments were significantly different with the 35% PAW treatment resulting in the highest average lint yield of 1880 lbs. lint/acre. The 50%, 65%, and 80% PAW treatments resulted in 1410, 1123, and 248 lbs. lint/acre respectively. There was no significant (P<0.05) difference between varieties within all PAW treatments in 1997. In 1998, all PAW depletion treatments again were significantly different with the 35% PAW treatment resulting in the highest average lint yield of 1658 lbs. lint/acre. The 50%, 65%, and 80% PAW treatments resulted in 1534, 1396, and 641 lbs. lint/acre respectively.
    • 1998 Cottonseed Variety and Fungicide Evaluation

      Knowles, Tim C.; Odom, Bruce; Wakimoto, Del; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Two upland cotton varieties (Deltapine 5415 and SureGrow 125) were subjected to various seed fungicide treatments to determine seedling emergence and vigor in a Mohave Valley field prone to Rhizoctonia infection of cotton seedlings. During 1998, cotton seedlings in this field exhibited symptoms associated with Rhizoctonia, Pythium, and Thielaviopsis fungi. Of the treatments examined in this study, Baytan+Thiram+Allegiance or Baytan+Ascend+Allegiance cotton seed treatments provided superior seedling disease protection. The Protégé+Allegiance fungicide treatment provided superior seedling disease protection when applied to Deltapine 5415 cotton seed, however seedling disease suppression was poor when the same treatment was applied to SureGrow 125. The Vitavax-PCNB+Allegiance and NuFlow M+Maxim+Apron were the least effective fungicide seed treatments examined in this study.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Sixteen long staple varieties were tested in a replicated small plot trial on the Safford Agricultural Center in Graham county at an elevation of 2950 feet. The highest yielding variety in this study was OA 340 with a yield of 1021 pounds of lint per acre. It was followed by two other Olvey varieties yielding over 900 pounds per acre, including OA 322 and OA 361 (White Pima). In the adjacent regional short staple cotton trial were three interspecific hybrids from Hazera, an Israeli Seed Company. These hybrids grew like short staple cotton, but the fiber was more like the barbadense parent. These hybrids yielded from 1146 to 1091 pounds per acre. Their data is included at the bottom of the tables for comparison with the other long staple variety values. Yield and other agronomic data as well as fiber quality data are contained in this paper.
    • Agronomic Comparison of Transgenic Varieties with their Parent Lines, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      As more transgenic varieties become available, grower=s interests intensify and more information is needed to satisfy the inquiries. Agronomic comparisons of six lines (transgenic varieties and their recurrent parents) from three companies are represented in this high desert study. Results show some subtle differences between the transgenic lines and their recurrent parents. Under the high Pink Bollworm pressure observed in the trial, yield increases were uniformly seen when the Bt gene was present, even though all plots were sprayed to control insect pests. Yields tended to be lower when herbicide resistence was introduced into the plants (even though not statistically significant), except when placed in a stacked array. Several agronomic values and HVI lint quality values are reported in this report.
    • Late Season Nitrogen Fertilizer for Cotton

      Knowles, Tim C.; Watson, Jack; Wakimoto, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Field experiments were conducted during the 1996 and 1997 growing seasons in Mohave Valley to determine the effect of late season nitrogen (N) fertilizer applications on top crop yield potential of upland cotton. A long season production system utilizing late season nitrogen (N) applications through peak bloom (August) was compared to a short season production system in which N was applied through mid-bloom (June). Mid-season N applications were based on UA guidelines utilizing plant mapping and petiole nitrate data for the short season production system.
    • Evaluation of Chemical Controls of Lygus hesperus in Arizona

      Ellsworth, Peter C.; Silvertooth, Jeff; The University of Arizona, Department of Entomology & Maricopa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      When other means fail to avoid damaging levels of an insect pest population, chemical control becomes necessary. Chemical control is a variable farm input which should be optimized to reduce economic damage by the pest while maximizing profit and minimizing exposure to secondary pest outbreaks, pest resurgence, and risks of insecticide resistance. To best balance these needs, a grower or PCA needs the best information possible for selecting and timing chemical controls. This study examines the array of Lygus chemical control options currently available as well as experimental compounds that may or may not be available in the future. While identifying the best chemical controls is the major objective of this study, insights into proper timing and duration of control are also discussed. In short, there are few, yet effective, Lygus insecticides available to growers currently. However, with proper rates and timing, significant yield protection can be achieved with Orthene® or Vydate®. To a lesser extent, Thiodan® (endosulfan) was also effective against Lygus, though higher rates than used in this study may be necessary to achieve acceptable control. The use of mixtures did not enhance control of Lygus over our two standards (Orthene or Vydate). Newer compounds were also studied; however, Mirids (plant bugs) are not worldwide targets for development by the agrochemical industry. Thus, most new compounds are effective on some other primary pest (e.g., whiteflies, boll weevil, thrips, aphids), and control of Lygus is merely a potential collateral benefit. Of these, the chloronicotinyls (e.g., Provado®, Actara®) were not practically effective against Lygus hesperus, in spite of their existing or pending labelling. Their labels are based on demonstrated efficacy against a related species present in cotton outside of the West (Lygus lineolaris). One compound shows excellent promise as a Lygus control agent, Regent® (fipronil). Under development by Rhône- Poulenc, this insecticide provides as good or better protection against Lygus than our best materials. In a system demanding multiple applications to control chronic Lygus populations, Regent could be key to the development of a sustainable use strategy that does not over rely on any single chemical class. None of the insecticides tested significantly controlled adult Lygus, except after repeated use and time. Even then, this effect was likely the result of generational control of the nymphal stage which thus produced fewer adults over time. Nymphal control was excellent for Orthene, Vydate, and Regent. Yields were up to five times higher in the best treatments relative to the untreated control. Other effects were also documented for the best treatments which have additional positive impact on grower profitability: shorter plants (better defoliation), higher lint turnouts, less gin trash, and a lower seed index.
    • 1998 Demonstration Project of Arizona Irrigated Cotton Production

      Dittmar, Stefan H.; Ellsworth, Peter C.; Hartman, Philip MacD; Martin, Edward C.; McCloskey, William B.; Olsen, Mary W.; Roth, Robert L.; Silvertooth, Jeffrey C.; Tronstad, Russell E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      The Demonstration project was conducted on the Demonstration Farm at the Maricopa Agricultural Center. In this project all current guidelines and recommendations disseminated by the University of Arizona were integrated in a systems approach. The management decisions were made by the Extension Specialists in agronomy, entomology, irrigation management, weed sciences, and plant pathology following the University recommendations. On a 50.5 acre field 80% Bt and 20% non-Bt cotton was planted dry and watered up. Due to the cold spring and sand-blasting, only a stand of 30,900 plants/A could be established with 84% terminal damage. 72 acreinches of water were used with 41.3 acre-inches in postplant irrigations. Weed control could be achieved with one preplant application and three cultivations. Three sprays against Lygus and one spray against whiteflies were necessary after the thresholds were exceeded. A total of 4120 lb seedcotton per acre were harvested, with 32.7% lint turnout (2.81 bales/A) and 45.9% seed turnout (1891 lb/A). After harvesting a field budget was established. The variable costs per acre were $915, the total cost $1266/acre. In spite of the lack of replications this project validates the usefulness and compatibility of University recommendations and the potential for integration of all disciplinary guidelines in one system.
    • Agronomic Evaluations of Transgenic Cotton Varieties, 1998

      Silvertooth, Jeffrey C.; Norton, Eric R.; Silvertooth, Jeff; University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Several field experiments were conducted in many of the cotton growing areas of Arizona in 1998 for the purpose of evaluating agronomic characteristics of many new transgenic Upland cotton varieties. In many cases, the new transgenic lines were compared directly with their recurrent (nontransgenic) parents. Evaluations were carried out by collecting plant mapping data from each variety on a regular 14 day interval throughout the season and relating the resultant information to established baselines for Upland cotton in Arizona. Lint yield measurements were also taken on each variety at all locations. Results indicate that all transgenic lines tested are very similar to their recurrent parents in terms of growth, development, and yield. Some subtle differences were noted but they were very slight and should not impact management of the varieties significantly in comparison to their recurrent parents.
    • Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1998

      Hart, G. L.; Nelson, J. M.; Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Thirty six upland cotton varieties were grown at the Maricopa Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent, plant populations, plant heights and fiber properties are presented in this paper.
    • Defoliation Tests with Ginstar at the Maricopa Agricultural Center in 1998

      Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Defoliation tests were conducted on upland and Pima cotton at the Maricopa Agricultural Center to evaluate the use of low rates of Ginstar for preconditioning cotton, several rates of Ginstar and tank mixes of Ginstar and Def. The upland cotton used in this test was generally difficult to defoliate, probably because of cool night temperatures. One application of Ginstar + Def gave acceptable defoliation of upland cotton 14 days after treatment (DAT) and this treatment was as good as using Ginstar as a preconditioner followed by Ginstar (2 applications of defoliant). For Pima cotton, most Ginstar treatments gave acceptable defoliation 7 DAT. Although defoliation treatments caused some leaf desiccation, it was not a serious problem in these tests. All defoliation treatments resulted in excellent control of terminal regrowth for both upland and Pima cotton.
    • How to Obtain Cotton Advisories from the Internet

      Brown, P.; Russell, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Weekly advisories developed by the Arizona Cotton Advisory Program are now available from the Internet. Nineteen location-specific advisories are developed each Monday morning and then transferred to the Main AZMET Internet Web Page located at URL address http://ag.arizona.edu/azmet. To retrieve advisories from the Internet users must 1) log on to the Internet using the procedures required by your Internet service provider; 2) enter the URL for the Main AZMET Web Page; 3) move to the Cotton Advisory sub-page; and 4) select the advisory of interest. Advisories for the most recent week, this year to date, and all of 1998 are available at this Internet address.